Which element has the same number of energy levels as aluminum (Al) and the same number of valence electrons as calcium (Ca)

Lead has an atomic number of 82. Which statement describes all neutral atoms and ions of lead?

IRINA_888 [86]

The neutral atom of lead must have 82 protons while ions can have b or less than 82.

The atomic number of an element is the number of protons in the nucleus of the element.

Also, for neutral atoms, the number of protons equals the number of electrons.

In ionic form, the number of protons/electrons of an atom may vary and be different from that of the neutral form.

Positive charges mean that the ion has less proton than its neutral version while negative charges mean that it has more electrons than its neutral version.

Thus, the neutral atom of lead will contain an equal number of protons as the electrons while its ionic form can have more or less than 82 protons.

More on atoms can be found here: brainly.com/question/803445?referrer=searchResults

6 0

2 years ago

Imagine a moving boat making waves in the middle of a pool of water. Also, imagine two observers, one behind the boat and one in

Simora [160]

The person who is behind the boat will see much powerful and bigger waves than the person who is in front of the boat. This phenomenon is caused by the Doppler effect which describes the changes in the observed frequency of a wave whenever there is relative motion between the wave source and the observer.

3 0

3 years ago

A sample of copper absorbs 4.31E+1 kJ of heat, resulting in a temperature rise of 6.71E+1 °C. Determine the mass (in kg) of the

olga2289 [7]

Answer: 1.67 kg

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

$Q=m\times c\times \Delta T$

Q = Heat absorbed= $4.31\times 10^1kJ$ = $43100J$ (1kJ=1000J)

m= mass of substance = ?

c = specific heat capacity = $0.385J/g^0C$

Change in temperature , $\Delta T=T_f-T_i=6.71\times 10^1^0C=67.1^0C$

Putting in the values, we get:

$43100J=m\times 0.385J/g^0C\times 67.1^0C$

$m=1670g=1.67kg$ (1kg=1000g)

Thus the mass (in kg) of the copper sample is 1.67

3 0

3 years ago

How much potassium chlorate would dissolve in 200g water at 20°C?

DedPeter [7]

Answer:

14 solubility in 200 gram of water at 20 c

Explanation:

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6 0

2 years ago

The reaction 2NO(g)+O2(g)−→−2NO2(g) is second order in NO and first order in O2. When [NO]=0.040M, and [O2]=0.035M, the observed

Oksanka [162]

Answer:

(a) The rate of disappearance of $O_{2}$ is: $4.65*10^{-5}$ M/s

(b) The value of rate constant is: 0.83036 $M^{-2}s^{-1}$

(c) The units of rate constant is: $M^{-2}s^{-1}$

(d) The rate will increase by a factor of 3.24

Explanation:

The rate of a reaction can be expressed in terms of the concentrations of the reactants and products in accordance with the balanced equation.

For the given reaction:

$2NO(g)+O_{2}->2NO_{2}$

rate = $-\frac{1}{2} \frac{d}{dt}[NO]$ = $-\frac{d}{dt}[O_{2}]$ = $\frac{1}{2}\frac{d}{dt}[NO_{2}]$ -----(1)

According to the question, the reaction is second order in NO and first order in $O_{2}$ .

Then we can say that, rate = k $[NO]^{2}[O_{2}]$ -----(2)

where k is the rate constant.

The rate of disappearance of NO is given:

$-\frac{d}{dt}[NO]$ = $9.3*10^{-5}$ M/s.

(a) From (1), we can get the rate of disappearance of $O_{2}$ .

Rate of disappearance of $O_{2}$ = $-\frac{d}{dt}[O_{2}]$ = (0.5)*( $9.3*10^{-5}$ ) M/s = $4.65*10^{-5}$ M/s.

(b) The rate of the reaction can be obtained from (1).

rate = $-\frac{1}{2} \frac{d}{dt}[NO]$ = (0.5)*( $9.3*10^{-5}$ )

rate = $4.65*10^{-5}$ M/s

The value of rate constant can be obtained by using (2).

rate constant = k = $\frac{rate}{[NO]^{2}[O_{2}]}$

k = $\frac{4.65*10^{-5}}{(0.040)^{2}(0.035)}$ = 0.83036 $M^{-2}s^{-1}$

(c) The units of the rate constant can be obtained from (2).

k = $\frac{rate}{[NO]^{2}[O_{2}]}$

Substituting the units of rate as M/s and concentrations as M, we get:

$\frac{Ms^{-1} }{M^{3}}$ = $M^{-2}s^{-1}$

(d) The reaction is second order in NO. Rate is proportional to square of the concentration of NO.

$rate\alpha [NO]^{2}$

If the concentration of NO increases by a factor of 1.8, the rate will increase by a factor of $(1.8)^{2}$ = 3.24

5 0

3 years ago